Levitation compensation method for dynamic electrostatic comb-drive actuators

An analytical method was developed for maintaining a constant levitation height during dynamic operation of reciprocating comb-drive actuators. The dependence of the translational position and the levitation height on the applied voltage was used to design waveforms that maintain a given translational motion without altering the levitation height. An experimental protocol was established for determining the necessary geometric factors of a particular comb-drive design, which were then used to generate constant-velocity levitation waveforms. The analytical model was tested experimentally by examining the levitation and translation positions of a surface micromachine under both compensated and uncompensated signals. A significant reduction in the range of levitation was obtained over the entire amplitude of the oscillatory motion, while the translational motion remained relatively unchanged. Design and fabrication effects on the compensated levitation height of an oscillating surface micromachine are discussed in the context of analytical and experimental results.